Antibacterial and antioxidant activities of shallot extract (Allium ascalonicum) on rainbow trout (Oncorhynchus mykiss) during chilled

Plant extracts are rich sources of natural antioxidant and antibacterial compounds. In recent decades, the need for using natural antioxidants in foods, pharmaceuticals and cosmetics has promopted extensive scientific research. The purpose of this investigation was to determine the antioxidant and antibacterial activities of shallot extract on shelf-life of vacuum-packaged gutted rainbow trout stored at 4±1˚C. Prepared fish were divided into two batches. One batch was treated by dipping in an aqueous solution of shallot extract, vacuum-packaged, and kept at 4±1˚C, serving as the treatment sample, and one batch was vacuum-packaged and served as control. Chemical (TVN, TBA, PV) and microbial (total viable count, psychrotrophic) tests were performed, pH measured, and sensory analysis done on all the samples kept for 20 days. Shallot extract delayed significantly (p<0.05) lipid oxidation in the treated sample, in which the psychotrophic bacteria and total viable counts also remained lower than the proposed acceptable limit (7 log cfu/g). Furtehrmore, microbial spoilage decreased significantly (p<0.05) in the treated, in comparison with the control, sample. According to sensory analysis results, treated samples were acceptable even at the end of the 20-day storage. The findings indicate that shallot extract exerts antioxidant and antibacterial effects on vacuum-packaged rainbow trout during storage and increases its shelf life.